BurstBalloons

// Author: Sayed Mahmudul Alam
// Source: LeetCode-452: https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons/description/
// Solution Ref: https://www.youtube.com/watch?v=uC0aDIhwGdE&t=431s&ab_channel=NareshGupta
// Example Input: points = [[10,16],[2,8],[1,6],[7,12]]
// Output: 2

class Solution {
    func findMinArrowShots(_ points: [[Int]]) -> Int {

        // if input array is empty then no arrow needed
        guard !points.isEmpty else { return 0 }

        // sort the array in descending order 
        let sorted = points.sorted { $0[1] < $1[1] }

        var arrow = 1
        var end = sorted[0][1]

        // check if the start of a point is greater then the `end`
        // if it's greater then will need another array and 'end' should be updated 
        for i in 1..<points.count {
            if sorted[i][0] > end {
                arrow += 1
                end = sorted[i][1]
            }
        }

        return arrow
    }
}